>> The autonomic nervous system, or ANS, plays a significant role in maintaining homeostasis. Most of the adjustments the ANS makes to the body are done subconsciously. For instance, when was the last time you told your arteries to constrict, or your pupils to dilate? The ANS takes care of these tasks and others for you. As a health care professional, it's very important for you to understand the anatomy and physiology of the autonomic nervous system for many reasons. One reason is that a thorough comprehension of the ANS is required in order to know how different types of drugs affect the nervous system and any side effects these drugs may cause. For example, it's critical that you know the location and function of different nerve fibers in the body, such as cholinergic and adrenergic fibers. These fibers release different neurotransmitters in the body, and specific drugs may target these chemical messengers or their receptors to stimulate or inhibit selected areas or organs of the body. As a nurse, you will monitor your patients for medication side effects, especially in situations where patients are unable to do so for themselves. For instance, some antidepressant drugs may cause anticholinergic side effects which may include dry mouth, blurred vision, constipation or difficulty urinating. Having a solid understanding of the autonomic nervous system will enable you to watch for potential side effects of medication in your patients and treat them as they occur.